What better way to hide a stealth satellite than to launch a satellite-shaped object of the same mass as the real thing, separate out the real deal, and claim the object is a failed satellite?
We don't even know which agency launched ZUMA, and there's no obligation for them to tell the press if it worked or not.
More information/speculation for anyone interested:
"The first of these satellites is known as the USA-53 or Misty satellite. This stealth satellite’s design means that it is incredibly difficult to detect or locate. This satellite is thought to have been developed to keep an eye on the Soviets and their concealment of weaponry. If this satellite is still really in place it remains classified information. Allegedly launched in 1990 (on board Space Shuttle Atlantis, STS-36), was a payload which remains top secret but openly known is that the mission was dedicated to the Department of Defense. Aviation Week magazine announced the satellite on-board was an imaging reconnaissance satellite. Amateur astronomers tracked the Shuttle and its payload and measured the satellite’s magnitude at -1, which was quite bright compared to normal imaging satellites.
A week after launch, reports were released from the Soviets that six bits of debris had been detected suggesting an explosion had occurred. The Pentagon announced that any debris would decay after six weeks. The amateur astronomers and observers that were tracking this object only catalogued five out of the six pieces. Six months later an unidentified satellite was discovered in orbit on a similar trajectory to that of the classified payload was released, leading the satellite spotters to suspect it was the missing piece, nick-named Misty. However a couple of noticeable manoeuvres later, Misty disappeared again. Perhaps the ‘explosion’ was a decoy to put Misty into place unbeknownst to the Russians."
Are the Russians really moving equipment out of sight every [orbital period here]? Or locating equipment out of the observational path?
Elsewhere in the comments, there is speculation of trying to hide an orbital refueling capability. This also seems like an obvious capability to already have, given the automated docking procedures used on the ISS for many years now.
This is outrages, as in the USA we should not have reason to do thing in the shadow or complete dark. What do they have to hide?
They might not tell the press but since its my tax dollars getting burned, I will call my congressman tomorrow and demand they will explain how my dollars are spent, and what was the purpose of this satellite.